<h3>Double digit subtraction</h3>
<p><%= link_to 'new question', :action => 'sdouble' %> | <%= link_to 'single', :action => 'ssingle'%></p>
<div id="problem"><p class="number"><%= @a %></p> <br/>
 <p class="number">- <%= @b %></p>
<hr>
<%= link_to_function "show answer", "Element.toggle($('answer')); return false;"%> <%= link_to 'next', :action => 'sdouble' %>
<div id="answer" style="display:none;">
<p class="number"><%= @a.to_i - @b.to_i %></p>
</div></div>